Re: [Xen-devel] [PATCH v3 8/8] ARM: make nr_irqs a constant

[Julien Grall <julien.grall@xxxxxxxxxx>]

Hi Andre,

On 01/02/18 13:43, Andre Przywara wrote:
> On 30/01/18 14:36, Roger Pau Monné wrote:
> > On Wed, Jan 24, 2018 at 06:10:58PM +0000, Andre Przywara wrote:
> > > On ARM the maximum number of IRQs is a constant, but we share it being
> > > a variable to match x86. Since we are not supposed to alter it, let's
> > > mark it as "const" to avoid accidental change.
> > >
> > > Suggested-by: Julien Grall <julien.grall@xxxxxxxxxx>
> > > Signed-off-by: Andre Przywara <andre.przywara@xxxxxxxxxx>
> > > ---
> > >   xen/arch/arm/irq.c        | 2 +-
> > >   xen/include/asm-arm/irq.h | 2 +-
> > >   2 files changed, 2 insertions(+), 2 deletions(-)
> > >
> > > diff --git a/xen/arch/arm/irq.c b/xen/arch/arm/irq.c
> > > index 62103a20e3..d229cb6871 100644
> > > --- a/xen/arch/arm/irq.c
> > > +++ b/xen/arch/arm/irq.c
> > > @@ -27,7 +27,7 @@
> > >   #include <asm/gic.h>
> > >   #include <asm/vgic.h>
> > >   
> > > -unsigned int __read_mostly nr_irqs = NR_IRQS;
> > > +const unsigned int __read_mostly nr_irqs = NR_IRQS;
> > Shouldn't you remove the __read_mostly attribute, so the symbol it's
> > placed at the .rodata section by the compiler?
> Yes, makes sense, thanks for pointing this out!
> const ... __read_mostly sounds somewhat redundant.
>
> It looks like the compiler does the right thing anyway, as I can't find
> nr_irqs in the ELF in any case. Both with and without __read_mostly it
> results into the very same binary, actually even without the const.
Really? I was expecting const data to be in the section.rodata. Are you 
suggesting this is landing in the section .data instead?
Cheers,

--
Julien Grall

_______________________________________________
Xen-devel mailing list
Xen-devel@xxxxxxxxxxxxxxxxxxxx
https://lists.xenproject.org/mailman/listinfo/xen-devel